JP2003-293836A, published by the Japan Patent Office in 2003, discloses a combustion control device for a diesel engine. The device controls gas flow in an engine cylinder along with a fuel injection timing and a fuel injection amount. For example, as a magnitude of the gas flow in the cylinder increases, the fuel injection amount is also increased so as to endure a penetration performance of injected fuel. As a penetration distance is increased, mixing of an injected fuel with air is further promoted, thereby preventing a fuel-excessive region, which is a source of smoke, from being formed in the cylinder.